Merge pull request #39 from cryptimeleon/develop

Release 3.2.0

Author: Jan Bobolz

CHANGELOG.md

@@ -5,6 +5,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ## [3.x] - 2021-09-21
 - A precompiled version of mcl is now packaged with mclwrap.
+- Added BLS12-381. 
 
 ## [2.x] - 2021-06-29
 - Made most of the mcl wrapper classes package-private.

README.md

@@ -4,7 +4,7 @@
 ![Build Status](https://github.com/cryptimeleon/mclwrap/actions/workflows/scheduled-main-ci.yaml/badge.svg)
 # Mclwrap
 
-Mclwrap provides a wrapper around the BN-254 bilinear group implemented in the [MCL library](https://github.com/herumi/mcl). As the bilinear groups implemented in the Cryptimeleon Math library are not particulary efficient, use of this wrapper is recommended for proper benchmarks.
+Mclwrap provides a wrapper around the BN-254 and BLS12-381 bilinear group implemented in the [MCL library](https://github.com/herumi/mcl). As the bilinear groups implemented in the Cryptimeleon Math library are not particulary efficient, use of this wrapper is recommended for proper benchmarks.
 Specifically, the Mclwrap implementation's group operations are roughly 100 times as fast as our own implementation.
 
 ## Security Disclaimer
@@ -21,7 +21,9 @@ Specifically, the Mclwrap implementation's group operations are roughly 100 time
 
 ## Quickstart
 
-Simply add mclwrap as a dependency (see below for [maven](#adding-mclwrap-dependency-with-maven) and [gradle](#adding-mclwrap-dependency-with-gradle) snippets) and start using the `MclBilinearGroup` in your code. 
+Simply add mclwrap as a dependency (see below for [maven](#adding-mclwrap-dependency-with-maven) and [gradle](#adding-mclwrap-dependency-with-gradle) snippets) and start using the `MclBilinearGroup` in your code.
+You can pass `GroupChoice.BN254` or `GroupChoice.BLS12_381` to the constructor of `MclBilinearGroup` to choose which group to use.
+Note that we currently do not support instantiating both groups at the same time.
 
 For full performance, you should compile the underlying mcl library for your system yourself (by default, a precompiled maximum-compatibility version of mcl is used, which may miss out on some modern processor features).
 Instructions for this can be found below. 

build.gradle

@@ -8,7 +8,7 @@ plugins {
 group 'org.cryptimeleon'
 archivesBaseName = project.name
 boolean isRelease = project.hasProperty("release")
-version = '3.1.0'  + (isRelease ? "" : "-SNAPSHOT")
+version = '3.2.0'  + (isRelease ? "" : "-SNAPSHOT")
 
 sourceCompatibility = 1.8
 targetCompatibility = 1.8
@@ -52,7 +52,7 @@ dependencies {
 
 test {
     useJUnitPlatform()
-    maxParallelForks 4
+    maxParallelForks = 1
     //we want display the following test events
     testLogging {
         events "PASSED", "STARTED", "FAILED", "SKIPPED"

src/main/java/com/herumi/mcl/Mcl.java

@@ -8,7 +8,7 @@
 
 package com.herumi.mcl;
 
-public class Mcl implements MclConstants {
+public class Mcl {
   public static void SystemInit(int curveType) {
     MclJNI.SystemInit(curveType);
   }

src/main/java/com/herumi/mcl/MclConstants.java

@@ -4,8 +4,8 @@
 import org.cryptimeleon.math.structures.groups.basic.BasicBilinearGroup;
 
 /**
- * A wrapper (with naive evaluation of operations) around the efficient type 3 Barreto-Naehrig pairing implementation
- * with a group order of 254 bits provided by the Mcl library.
+ * A wrapper (with naive evaluation of operations) around the efficient type 3 Barreto-Naehrig or BLS pairing implementation
+ * provided by the Mcl library.
  * <p>
  * Operation evaluation is done naively via {@link BasicBilinearGroup}.
  *
@@ -14,7 +14,11 @@
 public class MclBasicBilinearGroup extends BasicBilinearGroup {
 
     public MclBasicBilinearGroup() {
-        super(new MclBilinearGroupImpl());
+        this(MclBilinearGroup.defaultGroup);
+    }
+
+    public MclBasicBilinearGroup(MclBilinearGroup.GroupChoice groupChoice) {
+        super(new MclBilinearGroupImpl(groupChoice));
     }
 
     public MclBasicBilinearGroup(Representation repr) {

src/main/java/org/cryptimeleon/mclwrap/bn254/MclBasicBilinearGroup.java

@@ -4,8 +4,8 @@
 import org.cryptimeleon.math.structures.groups.lazy.LazyBilinearGroup;
 
 /**
- * A wrapper (with lazy evaluation of operations) around the efficient type 3 Barreto-Naehrig pairing implementation
- * with a group order of 254 bits provided by the Mcl library.
+ * A wrapper (with lazy evaluation of operations) around the efficient type 3 Barreto-Naehrig or BLS pairing implementation
+ * provided by the Mcl library.
  * <p>
  * Operation evaluation is done lazily via {@link LazyBilinearGroup}.
  * This class should be preferred over {@link MclBasicBilinearGroup} due to potential performance advantages.
@@ -14,11 +14,45 @@
  */
 public class MclBilinearGroup extends LazyBilinearGroup {
 
+    public enum GroupChoice {
+        BN254(0),
+        BLS12_381(5);
+        //, SECP256K1(102)
+
+        final int mclconstant;
+
+        GroupChoice(int mclconstant) {
+            this.mclconstant = mclconstant;
+        }
+    }
+
+    static final MclBilinearGroup.GroupChoice defaultGroup = MclBilinearGroup.GroupChoice.BN254;
+
     public MclBilinearGroup() {
-        super(new MclBilinearGroupImpl());
+        this(defaultGroup);
+    }
+
+    public MclBilinearGroup(GroupChoice groupChoice) {
+        super(new MclBilinearGroupImpl(groupChoice));
     }
 
     public MclBilinearGroup(Representation repr) {
         super(repr);
     }
+
+    /**
+     * Usually, you can only instantiate one of the Mcl groups (BN/BLS).
+     * If you try to instantiate the second one within the same JVM, you'll be met with an exception.
+     * This is a known limitation right now https://github.com/cryptimeleon/mclwrap/issues/5.
+     *
+     * Calling this method allows you to reset the group so that you can instantiate the "other" one.
+     * Please only call this if you know what you're doing. Existing GroupElements will be reinterpreted for the new group,
+     * so everything will behave pretty weirdly if you keep using them.
+     *
+     * This should be fine to do if you don't ever use the old Group/GroupElement/etc. objects anymore after calling this.
+     */
+    public static void resetMclInitializationAndAcceptErrors() {
+        MclBilinearGroupImpl.initializedGroup = null;
+        System.err.println("Resetting mcl initialization. Hope you know what you're doing.");
+    }
 }

src/main/java/org/cryptimeleon/mclwrap/bn254/MclBilinearGroup.java

@@ -15,38 +15,31 @@
 import java.nio.file.Files;
 
 /**
- * A wrapper around the efficient type 3 Barreto-Naehrig pairing implementation with a group order of 254 bits provided
- * by the Mcl library.
+ * A wrapper around the efficient type 3 Barreto-Naehrig or BLS pairing implementation provided by the Mcl library.
  *
  * @see <a href="https://github.com/herumi/mcl">Mcl library on Github</a>
  */
 class MclBilinearGroupImpl implements BilinearGroupImpl {
-    private static boolean isInitialized = false;
-    protected static MclGroup1Impl g1;
-    protected static MclGroup2Impl g2;
-    protected static MclGroupTImpl gt;
 
-    protected static MclHashIntoG1Impl hashIntoG1;
-    protected static MclHashIntoG2Impl hashIntoG2;
+    protected static MclBilinearGroup.GroupChoice initializedGroup = null;
+    protected MclGroup1Impl g1;
+    protected MclGroup2Impl g2;
+    protected MclGroupTImpl gt;
 
+    protected MclHashIntoG1Impl hashIntoG1;
+    protected MclHashIntoG2Impl hashIntoG2;
 
-    public MclBilinearGroupImpl() {
-        init(true);
+    public MclBilinearGroupImpl(MclBilinearGroup.GroupChoice choice) {
+        init(choice);
+        g1 = new MclGroup1Impl(choice);
+        g2 = new MclGroup2Impl(choice);
+        gt = new MclGroupTImpl(choice);
+        hashIntoG1 = new MclHashIntoG1Impl(g1);
+        hashIntoG2 = new MclHashIntoG2Impl(g2);
     }
 
     public MclBilinearGroupImpl(Representation repr) {
-        this();
-        if (!repr.str().get().equals("bn254")) {
-            throw new IllegalArgumentException("Invalid representation");
-        }
-    }
-
-    /**
-     * Returns true if the native library is available, false otherwise.
-     */
-    public static boolean isAvailable() {
-        init(false);
-        return isInitialized;
+        this(MclBilinearGroup.GroupChoice.valueOf(repr.str().get()));
     }
 
     protected static boolean loadIncludedLibrary(){
@@ -61,7 +54,7 @@ protected static boolean loadIncludedLibrary(){
             if(platformArch.equals("x86")){
                 requiredLibraryName="mcljava-win-x86.dll";
             }
-            if(platformArch.equals("amd64")){
+            if(platformArch.equals("amd64") || platformArch.equals("x86_64")){
                 requiredLibraryName="mcljava-win-x64.dll";
             }
         }
@@ -71,18 +64,19 @@ protected static boolean loadIncludedLibrary(){
             if(platformArch.equals("x86") || platformArch.equals("i386")){
                 requiredLibraryName="mcljava-linux-x86.so";
             }
-            if(platformArch.equals("amd64")){
+            if(platformArch.equals("amd64") || platformArch.equals("x86_64")){
                 requiredLibraryName="mcljava-linux-x64.so";
             }
         }
 
         if(platformName.contains("mac")){
-            if(platformArch.equals("amd64")){
+            if(platformArch.equals("amd64") || platformArch.equals("x86_64")){
                 requiredLibraryName="mcljava-mac-x64.dylib";
             }
         }
 
         if(requiredLibraryName == null){
+            System.err.println("Could not find precompiled library for "+platformName+" "+platformArch);
             return false;
         }
         InputStream nativeLibrary = MclBilinearGroupImpl.class.getResourceAsStream(requiredLibraryName);
@@ -117,44 +111,43 @@ protected static boolean loadIncludedLibrary(){
         return true;
     }
 
-    protected static void init(boolean printError) {
-        if (!isInitialized) {
-            String lib = "mcljava";
-            try {
-                System.loadLibrary(lib);
-            } catch (UnsatisfiedLinkError le) {
-                boolean couldLoadProvidedLibrary = loadIncludedLibrary();
-                if (printError && !couldLoadProvidedLibrary) {
-                    le.printStackTrace();
-                    String libName = System.mapLibraryName(lib);
-                    System.err.println("If you get this error, the required native library " + libName + " was not found and none of the included libraries could be used!");
-                    System.err.println("You need to retrieve the native mcljava library that is appropriate for your platform and install it into one of the lib directories:");
-                    System.err.println(System.getProperty("java.library.path"));
-                    return;
-                }
-                else if(printError){
-                        System.err.println("The required native mcl library was not found on this system, but one of the included pre-compiled libraries could be used.");
-                        System.err.println("mclwrap will work as expected, but for optimal run-time performance, please compile the mcljava library from source and install it into one of the lib directories:");
-                        System.err.println(System.getProperty("java.library.path"));
-                }
-            }
-            try {
-                // TODO: DO we want to offer the other curve type too?
-                Mcl.SystemInit(Mcl.BN254);
-            } catch (UnsatisfiedLinkError le) {
-                if (printError) {
-                    le.printStackTrace();
-                    System.err.println("mcl library was found, but its functions cannot be called properly");
-                }
+    protected static synchronized void init(MclBilinearGroup.GroupChoice groupChoice) {
+        if (initializedGroup == groupChoice)
+            return;
+        if (initializedGroup != null)
+            throw new IllegalArgumentException("mcl has already been initialized with " + initializedGroup + ", you're trying to instantiate " + groupChoice + ". " +
+                    "We currently do not support running multiple mcl settings at once. It's a known limitation of mcl's Java wrapper. " +
+                    "If you promise you won't use the old GroupElements anymore (or don't fear undefined behavior), you can call MclBilinearGroupImpl.resetMclInitialization() and then retry.");
+        //If you really, really want to make the two settings work concurrently, feel free to pull request that. It's nontrivial though.
+        //You'd need to adapt the Java wrapper in this project and the corresponding C code in mcl, see discussion here: https://github.com/cryptimeleon/mclwrap/issues/5.
+
+        String lib = "mcljava";
+        try {
+            System.loadLibrary(lib);
+        } catch (UnsatisfiedLinkError le) {
+            boolean couldLoadProvidedLibrary = loadIncludedLibrary();
+            if (!couldLoadProvidedLibrary) {
+                le.printStackTrace();
+                String libName = System.mapLibraryName(lib);
+                System.err.println("If you get this error, the required native library " + libName + " was not found and none of the included libraries could be used!");
+                System.err.println("You need to retrieve the native mcljava library that is appropriate for your platform and install it into one of the lib directories:");
+                System.err.println(System.getProperty("java.library.path"));
+                System.err.println("See README.md");
                 return;
+            } else {
+                System.err.println("The required native mcl library was not found on this system, but one of the included pre-compiled libraries could be used.");
+                System.err.println("mclwrap will work as expected, but for optimal run-time performance, please compile the mcljava library from source and install it into one of the lib directories:");
+                System.err.println(System.getProperty("java.library.path"));
+                System.err.println("See README.md");
             }
-            isInitialized = true;
-            g1 = new MclGroup1Impl();
-            g2 = new MclGroup2Impl();
-            gt = new MclGroupTImpl();
-            hashIntoG1 = new MclHashIntoG1Impl(g1);
-            hashIntoG2 = new MclHashIntoG2Impl(g2);
         }
+        try {
+            Mcl.SystemInit(groupChoice.mclconstant);
+        } catch (UnsatisfiedLinkError le) {
+            throw new RuntimeException("mcl library was loaded, but cannot be initialized", le);
+        }
+
+        initializedGroup = groupChoice;
     }
 
     @Override
@@ -199,7 +192,13 @@ public HashIntoGroupImpl getHashIntoGT() throws UnsupportedOperationException {
 
     @Override
     public Integer getSecurityLevel() {
-        return 100;
+        switch (g1.groupChoice) {
+            case BN254:
+                return 100; //https://tools.ietf.org/id/draft-yonezawa-pairing-friendly-curves-00.html "BN256"
+            case BLS12_381:
+                return 127; //https://tools.ietf.org/id/draft-yonezawa-pairing-friendly-curves-00.html
+        }
+        throw new IllegalArgumentException("unknown security level");
     }
 
     @Override
@@ -209,7 +208,7 @@ public BilinearGroup.Type getPairingType() {
 
     @Override
     public Representation getRepresentation() {
-        return new StringRepresentation("bn254");
+        return new StringRepresentation(g1.groupChoice.name());
     }
 
     @Override
@@ -219,6 +218,11 @@ public int hashCode() {
 
     @Override
     public boolean equals(Object obj) {
-        return obj instanceof MclBilinearGroupImpl;
+        return obj instanceof MclBilinearGroupImpl && ((MclBilinearGroupImpl) obj).g1.equals(g1);
+    }
+
+    @Override
+    public String toString() {
+        return g1.groupChoice.toString();
     }
 }

src/main/java/org/cryptimeleon/mclwrap/bn254/MclBilinearGroupImpl.java

@@ -9,8 +9,8 @@
 class MclGroup1Impl extends MclGroupImpl {
     protected MclGroup1ElementImpl generator = null;
 
-    public MclGroup1Impl() {
-        super();
+    public MclGroup1Impl(MclBilinearGroup.GroupChoice groupChoice) {
+        super(groupChoice);
     }
 
     public MclGroup1Impl(Representation repr) {
@@ -58,7 +58,13 @@ public MclGroup1ElementImpl getGenerator() throws UnsupportedOperationException
 
     @Override
     public double estimateCostInvPerOp() {
-        return 1.875;
+        switch (groupChoice) {
+            case BN254:
+                return 1.5;
+            case BLS12_381:
+                return 2;
+        }
+        throw new IllegalArgumentException("Unknown cost estimate.");
     }
 
 }